Method for producing a vehicle battery, vehicle battery and motor vehicle

Abstract

The invention relates to a method for producing a vehicle battery, wherein a plurality of battery cells are arranged (V1) next to one another with their central axes parallel to one another, each of the battery cells is electrically contacted at its end face by means of a cell contacting system, as a result of which the battery cells are electrically interconnected (V2), the battery cells are coated (V3) with an adhesion-promoting layer on their end face that is in contact with the cell contacting system, and a foam is foamed (V4) around the battery cells at least in the region of the end faces thereof that are in contact with the cell contacting system.

Description

[0001] Method for producing a vehicle battery, vehicle battery and motor vehicle

[0002] The invention relates to a method for producing a vehicle battery, a vehicle battery for a motor vehicle and a motor vehicle with a vehicle battery.

[0003] DE 10 2018 128 501 A1 discloses a method for coating a battery cell of a vehicle battery. In this method, the battery cell is coated with an insulating layer of paint. The paint layer is monitored using a control device. Depending on the monitoring, an insulating film is adhered to the paint layer, and a voltage is applied to the paint layer using the control device to monitor the paint layer.

[0004] Furthermore, an energy storage device for a motor vehicle is known from DE 10 2019 130 435 A1. The energy storage device comprises an actuator comprising a flame-retardant material and a casing. The flame-retardant material can comprise a layered structure with a primer, in particular an adhesion promoter, a first intumescent paint layer, a second intumescent paint layer, and a top coat.

[0005] The object of the present invention is to provide a solution which enables particularly safe foam encapsulation of a large number of battery cells of a vehicle battery.

[0006] This object is achieved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0007] The invention relates to a method for producing a vehicle battery which is designed to be used in a motor vehicle. In particular, the vehicle battery can be used in a motor vehicle, in particular in a passenger car. The vehicle battery is designed in particular to provide electrical energy for an electric drive train of the motor vehicle. The motor vehicle can thus be electrically driven by means of electrical energy from the vehicle battery. The vehicle battery can in particular be a so-called high-voltage battery. The method provides for a large number of battery cells to be arranged next to one another with their central axes parallel to one another. In this case, the battery cells can be arranged next to one another, for example, on a so-called cell carrier.In other words, a battery cell complex is formed from the plurality of battery cells, in which battery cells are positioned relative to one another. The method further provides that each of the battery cells is electrically contacted at its end face by means of a cell contacting system, whereby the battery cells are electrically interconnected. The cell contacting system can in particular comprise a plurality of cell connectors, which are each configured to directly connect two of the battery cells to one another, whereby the battery cells are interconnected in series and / or parallel via the cell contacting system. In particular, it is provided that at least one of the respective poles of all battery cells is arranged on the same side of the battery cell complex.This makes it possible to apply the cell contact system to only one side of the battery cell complex in order to interconnect all of the battery cell poles. The battery cells can be interconnected particularly easily if all of the battery cell poles, and thus both the positive and negative poles, are arranged on the end faces of the battery cells arranged on the same side of the battery cell complex. This makes it particularly easy for the cell contact system to electrically contact all of the battery cells, which in turn makes it particularly easy to install the vehicle battery. The method further provides for the battery cells to be coated with an adhesion-promoting layer on the end face that is in contact with the cell contact system.In this process, the battery cells are coated with the adhesion-promoting layer, at least in some areas on the end face contacting the cell contact system. It is planned that all battery cells will be coated with the adhesion-promoting layer on the end face contacting the cell contact system. Adhesion promoters are substances that create a close physical or, more often, chemical bond at the interface of immiscible materials. Adhesion promoters are also referred to as primers in some contexts. Adhesion promoters improve the adhesion of bonds and coatings to a substrate. The adhesion strength of coatings is defined as a measure of the resistance of a coating to mechanical separation from the substrate.

[0008] The method further provides for the battery cells to be foam-coated, at least in the area of ​​their end faces contacting the cell contact system. The adhesion-promoting layer thus serves to securely bond the foam to the battery cells. This ensures that this connection exhibits a cohesive fracture pattern in the event of failure. Cohesive fracture is a failure within a layer. In such a fracture behavior, the adhesion of the adhesion promoter to the battery cells or to the foam is greater than the internal strength of the adhesion-promoting layer or foam.In other words, the foam is held so tightly to the end faces of the battery cells by the adhesion-promoting layer that, in the event of failure, the fracture occurs in the adhesion-promoting layer and / or in the foam, but the foam does not detach from the adhesion-promoting layer, nor does the adhesion-promoting layer detach from the battery cells. The method thus enables the foam, which is used to foam the battery cells, to be held particularly securely to the battery cells, especially at their end faces.

[0009] In a possible further development of the invention, a varnish is applied as the adhesion-promoting layer. A varnish is a liquid or powder coating material that is applied thinly to objects and, through chemical or physical processes, builds up into a continuous, solid film. Applying the adhesion-promoting layer in the form of a varnish enables a particularly large-area, continuous coating of the respective end faces of the battery cells with the adhesion-promoting layer, thereby ensuring that the foam can be held particularly securely at least on the end faces of the respective battery cells.

[0010] In this context, it can be provided, in particular, that the applied varnish is cured by irradiation with UV rays. UV radiation stands for ultraviolet radiation, which covers a wavelength range from 100 nm to 400 nm. The varnish is therefore a UV-curing varnish. The use of the UV-curing varnish enables the varnish to be cured in a targeted and precisely controlled manner after application by irradiation with UV radiation. This can ensure reliable and uniform curing of the varnish. Furthermore, the varnish can cure particularly quickly through irradiation with UV rays.

[0011] In a further possible embodiment of the invention, an electrically insulating material is used as the adhesion-promoting layer. The adhesion-promoting layer is thus non-conductive and thus has only an extremely low and thus negligible electrical conductivity. This makes it particularly easy to prevent an electrical current flow between the end faces of the battery cells and other components of the vehicle battery, bypassing the cell contact system. In particular, this makes it possible to minimize the risk of short circuits within the vehicle battery. The adhesion-promoting layer thus fulfills the function of both an adhesion promoter and an electrical insulator.Since the adhesion-promoting layer can fulfill a particularly large number of functions, the vehicle battery can be designed to be particularly compact and lightweight, as it is not necessary to provide different elements for the different functions.

[0012] In a further possible embodiment of the invention, it is provided that round cells are used as battery cells. These round cells are at least substantially cylindrical in shape, wherein an axial direction of the respective battery cells coincides with a longitudinal extension direction of the central axis of the respective battery cells. Each of the battery cells has two end faces which are arranged on opposite sides of the battery cells with respect to the axial direction. In particular, it is provided that both a positive terminal and a negative terminal, and thus both the positive pole and the negative pole, are arranged on the same end face of the respective battery cells. The cell contact system therefore only needs to be connected to one of the end faces of the respective battery cell in order to interconnect the battery cells. The round cells can in particular be lithium-ion cells.

[0013] In this context, it can be provided, in particular, that the adhesion-promoting layer is applied at least in one region of a cell shoulder on the front side of the respective battery cells. The cell shoulder of the respective battery cells is located on one front side of the battery cells in a radial edge region of this front side, wherein the cell shoulder on the front side adjoins the edge of the lateral surface of the battery cell. The cell shoulder is thus located in the region of the transition between the front side and the lateral surface of the respective battery cell. By applying the adhesion-promoting layer at least in the region of the cell shoulder, particularly secure adhesion of the foam to the cell shoulder of the respective battery cell can be achieved. This allows particularly secure foaming of the respective battery cells to be achieved.

[0014] In this context, it can further be provided that the battery cells are covered with an electrically insulating film at least on their outer surface before being arranged next to one another. In other words, the battery cells are wrapped with the electrically insulating film on their outer surface and then arranged next to one another with their central axes parallel to one another. The electrically insulating film enables particularly reliable electrical insulation of the battery cells on their outer surface. After the battery cells have been arranged in the battery cell complex, in which the battery cells can be arranged with their outer surfaces adjacent to one another laterally, it can happen that certain outer surfaces of the battery cells are no longer accessible for subsequent electrical insulation, at least in some regions.By electrically insulating the battery cells at their outer surfaces before arranging the battery cells with their outer surfaces adjacent to one another, it can be ensured that the battery cells are reliably electrically insulated at their outer surfaces. Covering the battery cells with the electrically insulating film enables particularly simple and quick, reliable electrical insulation of all battery cells across their entire outer surface. In this case, electrical insulation of the battery cells is omitted at least on the end face that is to be contacted by the cell contact system in order to enable particularly simple connection of cell connectors of the cell contact system to the respective end faces of the battery cells after the battery cells have been arranged in the battery cell complex.If the battery cells were already electrically insulated at their end faces that are to be contacted with the cell contact system before being arranged in the battery cell complex, the battery cells would have to be stripped of their electrical insulation at least in some areas at these end faces before being connected to the cell contact system in order to enable electrical connection to the cell contact system. If the electrical insulation at the end faces is removed to enable connection to the cell contact system, particles of the electrical insulation could be released during grinding or laser removal, which could then contaminate the battery cell complex.Such contamination can be avoided in the presently described method by omitting the electrical insulation of the battery cells at their end faces to be connected to the cell contact system before arranging the battery cells in the battery cell complex and thus before connecting them to the cell contact system. After the battery cells have been arranged in the battery cell complex and have been electrically contacted with the cell contact system, the battery cells can be electrically insulated at least in some areas at their end faces by applying the adhesion-promoting layer, provided that the adhesion-promoting layer is simultaneously an electrically insulating coating.

[0015] In a further possible embodiment of the invention, it is provided that the adhesion-promoting layer is applied using a print head. The adhesion-promoting layer is thus applied to the end face of the respective battery cells using an overspray-free application process. The adhesion-promoting layer is thus printed at least partially onto the respective end faces of the battery cells. As a result, an area of ​​the respective end faces of the battery cells intended for coating can be provided with the adhesion-promoting layer with particular precision. For example, it is possible to exclude parts of the cell contact system from coating with the adhesion-promoting layer. The described method enables the adhesion-promoting layer to be applied in a particularly clearly defined manner in predetermined areas of the battery cells.

[0016] The invention further relates to a vehicle battery for a motor vehicle, having a plurality of battery cells, in particular round cells, which are arranged next to one another with their central axes parallel to one another. The vehicle battery further comprises a cell contact system with which the battery cells are each contacted at their end faces, whereby the battery cells are electrically interconnected. The battery cells are coated with an adhesion-promoting layer at least on their respective end faces contacted by the cell contact system. In addition, the battery cells are foam-enclosed at least in the region of their end faces contacted by the cell contact system. In particular, the battery cells are foam-enclosed with the foam in the region coated with the adhesion-promoting layer.This means that the foam is in direct contact with the adhesion-promoting layer and is held particularly securely to the battery cells via the adhesion-promoting layer. In particular, the vehicle battery was manufactured using a method as already described in connection with the method according to the invention for manufacturing a vehicle battery.

[0017] The invention further relates to a motor vehicle having a vehicle battery as already described in connection with the vehicle battery according to the invention. The motor vehicle is, in particular, a motor vehicle, in particular a passenger car, or in particular a motor cycle, such as a motorcycle.

[0018] Further features of the invention may emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0019] The drawing shows in the single figure (Fig. 1) a process diagram for a method for producing a vehicle battery for a motor vehicle

[0020] The method comprises method steps V1 to V4, which are carried out successively in the described order. In the first method step V1, it is provided that a large number of battery cells, which in the present case are designed as round cells, are arranged next to one another with their central axes parallel to one another. It can be provided that the battery cells are covered with an electrically insulating film at least on their outer surface before being arranged next to one another. In the second method step V2, each of the battery cells is electrically contacted at its end face by means of a cell contacting system, whereby the battery cells are electrically interconnected. In the third method step V3, it is provided that the battery cells are coated with an adhesion-promoting layer on their end face contacted by the cell contacting system.The adhesion-promoting layer is applied at least in one region of a cell shoulder on the end face of the respective battery cells. In this case, the adhesion-promoting layer is applied using a print head. It is provided that a lacquer is applied as the adhesion-promoting layer, which is subsequently cured by irradiation with UV rays. In this case, the adhesion-promoting layer is additionally designed to be electrically insulating. In the fourth method step V4 of the method, it is provided that the battery cells are foam-encapsulated at least in the region of their end faces contacting the cell contact system.

[0021] Foaming the cell pack formed from the multitude of battery cells makes it possible to avoid thermal propagation and absorb mechanical loads when the vehicle battery is used in a motor vehicle. In particular, the cell pack is foam-encased after it has been arranged in a storage housing of the vehicle battery. The storage housing with the foam-filled and foil-coated cell pack can meet mechanical requirements as part of a body structure of the motor vehicle. For this purpose, it is relevant that the foam forms a materially bond with at least part of the surface of the battery cells. To achieve this, the adhesion-promoting layer is applied selectively to at least part of a specific surface within the vehicle battery and thus not over the entire surface.In this case, the adhesion-promoting layer is applied at least partially to the end faces of the battery cells contacted by the cell contact system. In this case, the battery cells are provided with the adhesion-promoting layer at least in the area of ​​their respective cell shoulders in order to create a material-to-material bond between the battery cell shell of the respective battery cells and a foam surface of the foam. It is intended that this bond exhibits a cohesive fracture pattern in the event of failure. The adhesion-promoting layer is applied selectively, as it is applied during the advanced assembly process of the vehicle battery and relevant surfaces or attachments can thus be kept free of the coating. High standards of technical cleanliness must be met during the assembly process. In this case, the adhesion-promoting layer to be applied to the battery cells consists of UV-curing varnish.This coating acts as an adhesive bridge between the battery cell surface and the foam body formed from the foam, allowing for particularly effective transfer of mechanical loads between the foam and the battery cells. The UV coating can also act as electrical insulation, which is only required in selected areas of the vehicle battery, eliminating the need for extensive application.

[0022] The selective application of the adhesion-promoting layer takes place here by printing the battery cell surface using one or more jet printing nozzles. These jet printing nozzles can be guided in various ways, for example, by means of a robot, over the surface of the vehicle battery to be printed, in particular over the end faces of the battery cells to be printed. As an alternative to moving the jet printing nozzles using the robot, the at least one jet printing nozzle can be moved using a gantry system.

[0023] Overall, the invention shows how a selective application of a functional coating, in this case the adhesion-promoting layer, can be implemented by means of overspray-free application methods in the field of battery storage.

[0024] List of reference symbols

[0025] 5 V1 to V4 respective procedural steps

Claims

Patent claims 1. Method for producing a vehicle battery, in which a) a plurality of battery cells are arranged next to one another with their central axes parallel to one another (V1), b) each of the battery cells is electrically contacted at its end face by means of a cell contacting system, whereby the battery cells are electrically interconnected (V2), c) the battery cells are coated with an adhesion-promoting layer at their end face contacted with the cell contacting system (V3), d) the battery cells are foam-coated with a foam at least in the region of their end faces contacted with the cell contacting system (V4).

2. Method according to claim 1, characterized in that a lacquer is applied as an adhesion-promoting layer (V3).

3. Method according to claim 2, characterized in that the applied lacquer is cured by irradiation with UV rays (V3).

4. Method according to one of the preceding claims, characterized in that an electrically insulating material is used as the adhesion-promoting layer (V3).

5. Method according to one of the preceding claims, characterized in that round cells are used as battery cells (V1).

6. The method according to claim 5, characterized in that the adhesion-promoting layer is applied at least in a region of a cell shoulder on the end face of the respective battery cells (V3).

7. Method according to claim 5 or 6, characterized in that the battery cells are covered with an electrically insulating film at least on their outer surface before being arranged next to one another.

8. Method according to one of the preceding claims, characterized in that the adhesion-promoting layer is applied by means of a print head (V3).

9. Vehicle battery for a motor vehicle, with a plurality of battery cells which are arranged next to one another with their central axes parallel to one another, and with a cell contacting system with which the battery cells are each contacted at their end faces, whereby the battery cells are electrically interconnected, wherein the battery cells are coated with an adhesion-promoting layer at least on their respective end faces contacted with the cell contacting system and wherein the battery cells are foam-enclosed with a foam at least in the region of their end faces contacted with the cell contacting system.

10. Motor vehicle with a vehicle battery according to claim 9.

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